Semen parameters in fertile US men: the Study for Future Families

Abstract

Establishing reference norms for semen parameters in fertile men is important for accurate assessment, counseling and treatment of men with male factor infertility. Identifying temporal or geographic variability in semen quality also requires accurate measurement of semen parameters in well-characterized, defined populations of men. The Study for Future Families (SFF) recruited men who were partners of pregnant women attending prenatal clinics in Los Angeles CA, Minneapolis MN, Columbia MO, New York City NY and Iowa City IA. Semen samples were collected on site from 763 men (73% White, 15% Hispanic/Latino, 7% Black and 5% Asian or other ethnic group) using strict quality control and well-defined protocols. Semen volume (by weight), sperm concentration (hemacytometer) and sperm motility were measured at each center. Sperm morphology (both WHO, 1999 strict and WHO, 1987) was determined at a central laboratory. Mean abstinence was 3.2 days. Mean (median; 5th – 95th percentile) values were: semen volume, 3.9 (3.7; 1.5 – 6.8) ml; sperm concentration, 60 (67; 12–192) × 106/ml; total sperm count 209 (240; 32–763) × 106; % motile, 51 (52; 28–67) %; and total motile sperm count, 104 (128; 14–395) × 106, respectively. Values for sperm morphology were 11 (10; 3–20) % and 57 (59; 38–72) % normal forms for WHO, 1999 (strict) and WHO, 1987 criteria, respectively. Black men had significantly lower semen volume, sperm concentration and total motile sperm counts than White and Hispanic/Latino men. Semen parameters were marginally higher in men who achieved pregnancy more quickly but differences were small and not statistically significant. The SFF provides robust estimates of semen parameters in fertile men living in five different geographic locations in the US. Fertile men display wide variation in all of the semen parameters traditionally used to assess fertility potential.

Phthalate exposure and semen quality in fertile US men

“…The involvement of the Centers for Disease Control and Prevention (CDC) laboratory was determined not to constitute engagement in human subjects research. Further details of the study design have been described previously (Swan et al , 2003, Stokes-Riner et al ., 2007, Redmon et al , 2013). …”

“…In addition, models for ln(sperm concentration), ln(TSC) and ln(TMSC) were adjusted for abstinence time (as a continuous variable); models for motility were adjusted for time from sample collection to analysis, and time to complete analysis because motility decreases with time from sample collection; and models for morphology were adjusted for time to complete analysis. Covariates were selected a priori to be consistent with previous decisions about covariate adjustment for these outcomes in the SFF cohort (Swan et al ., 2003, Mendiola et al , 2010; Redmon et al ., 2013); all covariates selected were included in the final models. Standard residual-based plots were examined to assess the regression modeling assumptions of constant residual variance, linearity between covariates and outcome and normality of the residuals.…”

“…We use data collected from partners of pregnant women in the Study for Future Families, a large multi-center study designed to look at geographic variability in semen quality (Redmon et al , 2013). This population differs from those in most previous studies of phthalates exposure and semen quality in which participants were mainly recruited at infertility clinics (Duty et al ., 2005; Hauser et al ., 2006; Herr et al ., 2009; Jonsson et al ., 2005; Jurewicz et al ., 2013; Pant et al ., 2014; Wirth et al ., 2008).…”

Limitations of semen analysis as a test of male fertility and anticipated needs from newer tests

“…Epidemiological studies suggest that this may be related to the environmental toxicants though the association is controversial (3, 20–22). There are also differences in sperm concentration across racial/ethnic groups (23). More recent studies suggest that obesity is associated with suppression of the hypothalamic-pituituary-testis axis (24) and morbid obesity may be associated with decreased sperm concentration and reduced fertility (25–29).…”

Sperm Competition in Humans: Mate Guarding Behavior Negatively Correlates with Ejaculate Quality

“…All participants were of Western European descent in order to control for the possible influence of race on ejaculate parameters [43], [44]. Participants were aged between 18 and 35 years (mean ± 1SD, 24.20±4.72), as sperm quality is known to decline after the age of 35 years [45].…”